This invention relates to the improved delivery of additive materials to smoking articles. More particularly, this invention relates to providing additive materials in sealed containers that are opened during use to modify the characteristics of smoking articles.
It is known to provide a smoking article with additive materials to modify the characteristics of the smoking article. Additive materials typically modify the characteristics of the smoking article by passing gases, more particularly the hot, gaseous by-products of combustion, through the portion of the smoking article containing the additive material.
For example, sodium and/or calcium permanganate Ca(MnO.sub.4).sub.2 or NaMnO.sub.4 with colloidal silica deposited onto silica gel or alumina has been incorporated into filter elements to reduce smoke components such as NO, HCN, etc., as are disclosed in U.S. Pat. Nos. 3,957,059 and 4,637,408 to which the reader is referred. Menthol and other flavorants deposited on carbon, silica, and other activated particles in the filter section of a smoking article have been used to impart a flavor or taste to the smoking article. It also is known to provide a smoking article having a substantially tasteless fuel element with a flavor generator that, upon exposure to heat, provides an aerosol or vapors of flavorants to give the article its desired characteristics.
One of the problems with adding additive materials to smoking articles is that the active agents of the additive materials deactivate or volatize with time so that they do not have the desired effect upon use. Further, flavorant materials may be extensively trapped by components of the smoking articles so that less than desired amounts are delivered to the smoker. For example, a significant amount of menthol is trapped on active carbon or in cellulose acetate fibers of a conventional cigarette. Adding excess additive materials to compensate for expected loss of activity or entrapment results in inconsistent products because of variations in storage time prior to use and the conditions under which the article is consumed. The rigorous controls over product storage conditions and shelf life that would be required to minimize the volatility or deactivity of the active agent in the additive material are not commercially practical.
Another problem is that the active agents deactivate with the absorption of moisture or other volatile materials during storage or can migrate to the wrapper or embed in the filter or carrier of the smoking article so that they will not modify the smoke characteristics as desired.
A problem with adding additive materials to filter portions of smoking articles is that the filter containing, for example, the carbon activated particles on which menthol is conventionally deposited is closer to the burning end of a smoking article than is desirable, thus resulting in inefficient or unsatisfactory use of or undesired combustion or pyrolysis of the additive.
Accordingly, there is a continuing need to provide for improving the effective and efficient delivery of additive materials for modifying the characteristics of smoking articles under widely varying storage conditions.